From mboxrd@z Thu Jan 1 00:00:00 1970 From: Srinivas Kandagatla Subject: Re: Failure booting DragonBoard APQ8060 after mach-qcom introduction Date: Mon, 11 Aug 2014 17:35:49 +0100 Message-ID: <53E8F0E5.3010805@linaro.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pd0-f171.google.com ([209.85.192.171]:59926 "EHLO mail-pd0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752954AbaHKQfz (ORCPT ); Mon, 11 Aug 2014 12:35:55 -0400 Received: by mail-pd0-f171.google.com with SMTP id z10so11038680pdj.16 for ; Mon, 11 Aug 2014 09:35:55 -0700 (PDT) In-Reply-To: Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Linus Walleij , Kumar Gala , "linux-arm-msm@vger.kernel.org" Cc: Bjorn Andersson Hi Linus, On 11/08/14 13:49, Linus Walleye wrote: > On Mon, Aug 11, 2014 at 1:42 PM, Linus Walleij wrote: >> On Mon, Aug 11, 2014 at 1:21 PM, Linus Walleij wrote: >> >>> The symptom is that not even earlyprints come up if I put some >>> printascii() in start_kernel. >> >> Bah that was me not realizing that the defaults for DEBUG_UART_PHYS >> and DEBUG_UART_VIRT has to be set up properly... now I get the >> earlyprints. >> >> It seems to hang in the gsbi driver probe, off to debug. > > It appears that this oneliner gets the kernel booting again: > > diff --git a/drivers/soc/qcom/qcom_gsbi.c b/drivers/soc/qcom/qcom_gsbi.c > index 447458e696a9..1759a3c9140a 100644 > --- a/drivers/soc/qcom/qcom_gsbi.c > +++ b/drivers/soc/qcom/qcom_gsbi.c > @@ -57,7 +57,7 @@ static int gsbi_probe(struct platform_device *pdev) > /* make sure the gsbi control write is not reordered */ > wmb(); > > - clk_disable_unprepare(hclk); > + //clk_disable_unprepare(hclk); > > return of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev); > } > > The kernel hangs during disable/unprepare of the hclk for the GSBI. > Turning off hclk's could be dangerous if there are vital system > components using the hclk which does not yet have a reference > taken in the kernel, due to missing drivers or similar. > There is a patch to fix this http://www.spinics.net/lists/linux-arm-msm/msg09633.html > Any ideas? IMO, hclk is also used by the serial IP, disabling the clock while its being used by early printk would result in hang, I think that's what you are seeing. --srini > > Yours, > Linus Walleij > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >